Cardiovascular actions of desflurane with and without nitrous oxide during spontaneous ventilation in humans

We investigated the cardiovascular actions of desflurane (formerly I-653) during spontaneous ventilation. We gave 0.8-0.9, 1.2-1.3, and 1.6-1.7 MAC desflurane in oxygen (n = 6) and in 60% nitrous oxide, balance oxygen (n = 6) to unmedicated healthy male volunteers. Both anesthetic regimens decreased ventilation, increased partial pressure of arterial carbon dioxide, and produced similar cardiovascular changes. In comparison with values obtained when the volunteers were conscious, desflurane anesthesia with spontaneous ventilation decreased systemic vascular resistance and mean arterial blood pressure. Cardiac index, heart rate, stroke volume index, and central venous blood pressure increased. Left ventricular ejection fraction increased at 0.83 MAC desflurane in oxygen, and otherwise did not differ from the conscious value. The velocity of ventricular circumferential fiber shortening, estimated by echocardiography, increased with desflurane in oxygen but did not change with desflurane in nitrous oxide. Oxygen consumption increased during desflurane and oxygen anesthesia, but not when nitrous oxide plus oxygen was the background gas. Desflurane increased oxygen transport, the ratio of oxygen transport to oxygen consumption, mixed venous partial pressure of oxygen, and oxyhemoglobin saturation. The cardiovascular changes with desflurane during spontaneous ventilation differ from those during controlled ventilation. With both background gases, spontaneous ventilation, in comparison with controlled ventilation, increased cardiac index, stroke volume, central venous pressure, left ventricular ejection fraction, velocity of circumferential fiber shortening, oxygen transport, and the ratio of oxygen transport to oxygen consumption but did not change mean arterial blood pressure except at 1.66 MAC desflurane in oxygen (when it was higher with spontaneous than with controlled ventilation).